Tecnai on-line help manual -- Alignments - UT Southwestern

<strong>Tecnai</strong> on-line help Alignments 28<strong>Tecnai</strong> 12 Software version 2A common consequence of a diffraction shift that has not been aligned is a mismatch between the imagedetail selected with the selected area aperture and the area actually contributing to the diffractionpattern. When the image coils have not been aligned properly, image and diffraction shift are notuncoupled and the diffraction shift will also cause an image shift, thereby moving the image detail out ofthe selected area aperture.ProcedureThe alignment procedure consists of three steps:• A preparation step for setting up the image.• Two steps in which the X and Y pivot points are aligned.DescriptionThe alignment of the pivot points of the image deflection coils is essential to the proper functioning ofmany other alignments and calibrations: image shifts, diffraction shifts, detector alignments andmeasurement functions.The image coils pivot points (image shift and diffraction shift) alignment is reasonably insensitive to theoperating conditions and normally needs to be done only once. It is important that the image coils pivotpoints are aligned prior to aligning other parts of the microscope where the image coils are used,otherwise the latter alignments may have to be redone. Alignments where the image coils are used arethose where images or diffraction patterns are moved (image shift, diffraction shift/diffraction alignment).Misaligned diffraction shift pivot point.Aligned diffraction shift pivot point.6.4 Objective Lens preset SAPurpose: Setting the eucentric focus preset at the eucentric height.Importance: CONVENIENCE for having the eucentric focus at the eucentric height.Method: Focus the image for the highest SA magnification.Procedure• The alignment procedure consists of two steps:• A preparation step in which the SA image is focused at an intermediate magnification.• A step in which the highest SA magnification must be focused.